Bowel disease researchers find Viagra could be a remedy

Scientists believe they have found the cause of Crohn's disease, an unpleasant and intractable bowel disorder that affects one in every thousand people in the UK - and they think it could be treated with Viagra.

The team from University College London say that the cause is the opposite of what has been supposed. Crohn's causes acute ulceration and inflammation in the gut and was thought to be an auto-immune disease - an attack on the tissues by the body's defensive immune system, treated with immuno-suppressant drugs. But a long series of investigations led by Anthony Segal and colleagues has led to the discovery that people with Crohn's have a weak and unresponsive immune system which does not repair damage easily. Because the flow of blood to damaged cells is substantially reduced, a drug like Viagra, best known for its effects on erectile dysfunction, could help the healing process as it stimulates blood flow.

Professor Segal says that pinpointing the cause of Crohn's is "a very, very significant discovery". There have been many theories as to the cause of Crohn's since it was identified in the 1920s. Many believed it was caused by infection and there were some similarities with tuberculosis. "People have tried to find an infectious agent," he said. "But they haven't found one."

The researchers, whose work is published in the Lancet today, carried out biopsies on people with Crohn's, and some without. They discovered a difference in the number of white blood cells called neutrophils produced by the body to heal the damage in the bowel and on the surface of the skin. Healthy people produce far more neutrophils than Crohn's sufferers, showing that the immune response in people with Crohn's is damaged.

The scientists then tested the response of the patients' immune systems to bacteria such as might be found in the gut. The blood flow to the site of the bacteria increased 10-fold in healthy people, as the body mounted a repair operation. But in people with Crohn's the blood flow increased to four times the normal rate, and only doubled in those with bowel disease.

Viagra increased the blood flow. Prof Segal and colleagues now hope to run a clinical trial to establish whether that drug or a similar one can help guts ulcerated by Crohn's to heal.

But he stressed that patients who are on medication should not now suddenly switch.